Scheduling Algorithms

[ThorisoMakhosa]

Hi Everyone.

I am experimenting with scheduling algorithms for different use cases, most of the work has been mainly theoretical. Can i ask which scheduling algorithms does srsRAN currently support and how do i configure them for deployment scenarios since they are not available on the configuration files.

Thank you very much

[herlesupreeth]

Can i ask which scheduling algorithms does srsRAN currently support and how do i configure them for deployment scenarios since they are not available on the configuration files.

srsRAN_Project currently support Round-Robin and Proportional Fair scheduling. Round-Robin is used by default. In order to use PF scheduler you can configure it as follows:

cell_cfg:
  sched_expert_cfg:
    policy_sched_cfg:
      pf_sched:
        pf_sched_fairness_coeff: 2.0

[fahad-ece]

Dear @herlesupreeth

Is it possible to allocate/prioritize the resources based on the CQI/RSRP values shared by the COTS UE? Looking for your valuable feedback in this regard. Thank you.

[pgawlowicz]

the available schedulers are implemented here: https://github.com/srsran/srsRAN_Project/tree/main/lib/scheduler/policy

You can create a new one and implement the logic you want.

[fahad-ece]

Dear @pgawlowicz,

Thanks a lot for your prompt feedback. I am going through it now.

[netuska]

Hello every one, @herlesupreeth @pgawlowicz. I am new to the srsRAN and I need to impliment two scheduling strategies round_robins and Proportional fair. can you please tell me which file I need to modify to switch from rr to pf.
I appreciate your contributions.

[fahad-ece]

Hello every one, @herlesupreeth @pgawlowicz. I am new to the srsRAN and I need to impliment two scheduling strategies round_robins and Proportional fair. can you please tell me which file I need to modify to switch from rr to pf. I appreciate your contributions.

Hi @netuska,

You just need to modify the "gnb config file". By default the srsRAN gNB is configured for RR. If you want to switch to PF, just have look into past comments made by @herlesupreeth and @pgawlowicz. There are hundreds of matrices you can explore by modifying the gNB. If time permits, have a look into this link: https://docs.srsran.com/projects/project/en/latest/user_manuals/source/config_ref.html
Thank you.

[SRMK2000]

Hello,

I am trying to simulate the Proportional Fair (PF) scheduling algorithm, but I am observing the same behavior as Round Robin (RR) scheduling. I suspect the reason is that all User Equipment (UEs) are receiving the same Channel Quality Indicator (CQI) values, even when I modify the channel path loss parameters.

Since the PF algorithm relies on CQI values for scheduling decisions, I believe this issue is preventing it from functioning correctly.
My Questions:

Is there any additional configuration needed to ensure CQI values change dynamically based on channel conditions (e.g., path loss, fading, etc.)?
What parameters or settings should I check to ensure the CQI calculation reflects real channel variations?
Are there specific logs or debugging steps I can follow to verify if CQI values are being updated correctly?

I would appreciate any guidance on resolving this issue. Thank you!

[frankist]

yeah with the same cqi, it is hard to see the difference. Can you share your config?

[SRMK2000]

Hello @frankist and thanks for your answer
yes sure this the gnb.conf that i am using

This configuration file example shows how to configure the srsRAN Project gNB to allow srsUE to connect to it.

This specific example uses ZMQ in place of a USRP for the RF-frontend, and creates an FDD cell with 10 MHz bandwidth.

To run the srsRAN Project gNB with this config, use the following command:

sudo ./gnb -c gnb_zmq.yaml

cu_cp:
amf:
addr: 10.53.1.2 # The address or hostname of the AMF.
port: 38412
bind_addr: 10.53.1.1 # A local IP that the gNB binds to for traffic from the AMF.
supported_tracking_areas:
- tac: 7
plmn_list:
- plmn: "00101"
tai_slice_support_list:
- sst: 1
inactivity_timer: 7200 # Sets the UE/PDU Session/DRB inactivity timer to 7200 seconds. Supported: [1 - 7200].

ru_sdr:
device_driver: zmq # The RF driver name.
device_args: tx_port=tcp://127.0.0.1:2000,rx_port=tcp://127.0.0.1:2001,base_srate=23.04e6 # Optionally pass arguments to the selected RF driver.
srate: 23.04 # RF sample rate might need to be adjusted according to selected bandwidth.
tx_gain: 75 # Transmit gain of the RF might need to adjusted to the given situation.
rx_gain: 75 # Receive gain of the RF might need to adjusted to the given situation.

cell_cfg:
dl_arfcn: 368500 # ARFCN of the downlink carrier (center frequency).
band: 3 # The NR band.
channel_bandwidth_MHz: 20 # Bandwith in MHz. Number of PRBs will be automatically derived.
common_scs: 15 # Subcarrier spacing in kHz used for data.
plmn: "00101" # PLMN broadcasted by the gNB.
tac: 7 # Tracking area code (needs to match the core configuration).
pdcch:
common:
ss0_index: 0 # Set search space zero index to match srsUE capabilities
coreset0_index: 12 # Set search CORESET Zero index to match srsUE capabilities
dedicated:
ss2_type: common # Search Space type, has to be set to common
dci_format_0_1_and_1_1: false # Set correct DCI format (fallback)
prach:
prach_config_index: 1 # Sets PRACH config to match what is expected by srsUE
pdsch:
mcs_table: qam64 # Sets PDSCH MCS to 64 QAM
pusch:
mcs_table: qam64 # Sets PUSCH MCS to 64 QAM

log:
filename: /tmp/gnb.log # Path of the log file.
all_level: info # Logging level applied to all layers.
hex_max_size: 0

pcap:
mac_enable: false # Set to true to enable MAC-layer PCAPs.
mac_filename: /tmp/gnb_mac.pcap # Path where the MAC PCAP is stored.
ngap_enable: false # Set to true to enable NGAP PCAPs.
ngap_filename: /tmp/gnb_ngap.pcap # Path where the NGAP PCAP is stored.

[frankist]

How are you setting the PF scheduler? Can you show me what parameters did you change?

[SRMK2000]

I am editing the gnb,conf and add these lines

sched_expert_cfg:
policy_sched_cfg:
qos_sched:
pf_fairness_coeff: 2

I think it work fine but we cant see the difference between the 2 scheduler because of CQI

[frankist]

yeah, to see the PF algorithm in action, you should have different CQIs.